The geometrical and electronic properties and growth patterns of the bimetal Pd-2 doped Si-n (n = 10-20) clusters have been studied systematically by density functional theory. The growth-pattern behaviors, relative stabilities, and chemical bonding of these clusters are presented and discussed. The optimized geometries exhibit that the dominant growth patterns of Pd2Sin (n = 10-20) are based on the pentagonal prism PdSi10. The bimetal Pd-2 is doped on the opened cage-like silicon clusters (Si-n) with the range of size n = 10-15, while doped on bigger silicon clusters (Si-n, n = 16-20), the Pd-2 are completely encapsulated inside Si-n frames. The geometrical configurations of the encapsulated Pd-2 in the Si-n frames are varied due to the interactions between Pd-2 and Si-n frames. The calculated fragmentation energies reveal that the remarkable stable Pd2Sin clusters with n = 11, 13, 16, 18, and 20 are observed. Among all different-size clusters, the Pd-2-doped Si-16 is the most stable cluster. Particularly, the cage-like Pd2Si16 geometry is obviously distinct as compared to the single transition metal doped silicon cluster. Interestingly, the critical size of geometry transition is explored at n = 16. Natural population analysis manifests that the charge-transfer phenomena in the Pd-2-doped Si-n clusters are similar to those of the single TM doped silicon clusters. In addition, the Pd2Sin (n = 10, 13, 14, 16, and 17) isomers have enhanced chemical stabilities because of their larger gaps between the highest occupied orbital and the lowest unoccupied orbital. (C) 2014 Elsevier B.V. All rights reserved.